Investigating an Innovative Constructed Wetland Design for Removing Endocrine Disrupting Compounds from Reclaimed Wastewater
Project ID: 9589
Principal Investigator: Chris Holdren
Research Topic: Desalination and Water Treatment
Priority Area Assignments: 2014 (Advanced Water Treatment), 2015 (Advanced Water Treatment)
Funded Fiscal Years: 2013 and 2014
Keywords: wetlands, water reuse, endocrine disrupting compounds
What is the performance efficiency of constructed wetlands in removing organic wastewater compounds (OWC) and endocrine disrupting compounds (EDC) from municipal wastewater treatment plant effluent?
Presently in many parts of the arid western US, publically owned treatment works rely on direct or indirect reuse of reclaimed wastewater to meet increasing water demands. Treatment wetlands have been widely used to polish effluent from municipal, industrial, and agricultural wastewater treatment facilities by a complex interaction of physical, chemical, and biological processes that reduce concentrations of suspended solids, nutrients, dissolved organic carbon, volatile organic compounds, biochemical oxygen demand, and coliform bacteria. Proper design is important however, to ensure that essential components are functioning properly for the natural processes to occur at their optimum.
Recently there has been worldwide concern over the fate of water borne consumer product chemicals such as pharmaceuticals, hormones, and other EDCs and their potential effects on aquatic ecosystems and human health. These compounds are ubiquitous in wastewater treatment plant effluents and at combined concentrations they have the potential to impact the reproductive health of fish and interfere with ecosystem function. While wetlands perform many of the processes known to break down or attenuate EDCs, effective removal has not been verified or optimized at the demonstration scale and numerous critical data gaps remain with regards to incorporating wetlands into the public supply system. The research being proposed as part of this study will provide an opportunity to obtain unique insight into these issues, all of which are critical to ensure public health & safety and healthy ecosystems downstream.
[Sartoris et al. 2000; Barber et al. 2001; Keefe et al. 2004; Kadlec 2009].
(Mitsch and Gosselink 2000).
(NRC 1999; USEPA 2005; Vajda et al. 2008; Schoenfuss et al.
Need and Benefit
The concept of indirect potable reuse is defined as the process of using reclaimed water for potable purposes by discharging wastewater to a water supply source, such as a surface water or groundwater, and then using this supply source to dilute and/or treat the reclaimed water through natural processes. The mixed reclaimed/natural water may then receive additional treatment before entering the drinking water distribution system. Indirect potable reuse is showing great potential as a significant water supply strategy across the U.S. Not only is it generally less expensive than alternative supplies, it tends to garner a lot of support from environmental advocates because associated wetlands can provide valuable habitat for fish and wildlife species, particularly migratory birds. However, critical knowledge gaps remain, particularly as it relates to identifying wetland characteristics that potentially affect treatment effectiveness for contaminants relevant for indirect potable reuse (i.e., hydraulic retention time, short-circuiting, selective planting strategies, etc).
According to the Texas State Water Plan, approximately 1.6 million acre-feet per year (15 percent) of Texas' 2060 water supply needs will need to be provided through either the direct or indirect reuse of wastewater. To advance reuse in Texas, the TWDB completed a research agenda in February 2011 which identified research on the performance of constructed treatment wetlands in improving reclaimed water quality as the second highest research priority of the State.
Endocrine disrupting compounds often found in municipal wastewater have uncertain impacts on endangered species and human health. Some impacts on the Santa Ana sucker have been identified. Regulators are in the process of monitoring these EDCs. Wetlands can be cost effective strategies to mitigate EDCs; however, quantification of EDC reductions through wetland treatment has not occurred. This S&T project would provide the data necessary to validate constructed wetlands as low energy treatment units for EDCs, and could be widely utilized by our water district partners in complying with future EDC regulations.
During the recent and continuing drought, the fact of water reuse has become more apparent. People can see that no rain has fallen and the only input to the local reservoir is from the wastewater treatment plant. During times of drought, natural wetland systems are all that separates the wastewater effluent from someone's drinking water influent. A better understanding of the capability of natural treatment systems may give us clearer insight into the degree of treatment necessary for direct water reuse.
This information was last updated on August 1, 2014
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